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November 8, 2010

Moms: Ask for a Little Help from Friends

by Sam Savage

(Ivanhoe Newswire) -- A new study proves friendship is a powerful resource, especially for mothers. Female dolphins that have help from their female friends are far more successful as mothers than those without such help, according to this new study.

Previous research into reproductive success in animal populations has had mixed findings. Some studies point to the benefits of inherited genetic characteristics, while others show the benefits of social effects, such as having an aunt or uncle.

The new study is the first to look at the effects of these factors together in a wild animal population and has shown that social and genetic effects are both important for reproduction.

"Surprisingly, the genetic and social effects on reproduction have never been studied together in natural populations," Dr Bill Sherwin of the UNSW School of Biological, Earth and Environmental Sciences and lead author of the study was quoted as saying. "One of my doctoral students, Celine Frere, who led the latest study, realized that we could do so by using the long-term observations about which females were associating with each other, and putting that together with what we knew about their genetic relationships."

Dr. Frere found that a female's calving success is greater either by social association with other females that had high calving success, or by the female having relatives who are good at calving.

"Not only that, but the social and genetic effects interact in an intriguing way," says Dr Sherwin. "Having successful sisters, aunts and mothers around certainly boosts a female's calving success. But the benefits of social associates were more important for female pairs who were less genetically related."

SOURCE: Proceedings of the National Academy of Sciences, published online November 1, 2010